1. Field of the Invention
The present invention relates to a sensor arrangement for controlling an implantable device, such as a heart pacemaker, and in particular to a sensor arrangement which is connected to an evaluation circuit via a catheter having at least two leads (bipolar catheter).
2. Description of the Prior Art
A sensor arrangement for a heart pacemaker is described in German OS No. 31 52 963. In this sensor arrangement, the blood oxygen saturation is acquired using a sensor disposed in a heart chamber, the sensor being connected to the heart pacemaker via a dual-pole catheter. In some instances, however, the acquisition of a plurality of measured parameters is desirable. In the case of heart pacemakers, for example, the blood oxygen saturation, the blood temperature, the blood pressure and the conductivity of the blood provide information about the frequency at which the heart pacemaker should stimulate the heart. Sensors for individually obtaining all of the above parameters cannot be accomodated in the heart pacemaker itself, so that the measured signals must be transmitted via the catheter. It is important that the catheter, however, contain the fewest possible number of leads for reasons of flexibility and reliability.